A windows technique for sustentaculum tali screw fixation using the sinus tarsi approach for calcaneal fractures: a cadaveric study

Abstract

Introduction: The minimally invasive approach for displaced intra-articular calcaneal fractures is significantly reducing postoperative wound complications. One minimally invasive method, the sinus tarsi approach (STA) has been increasingly widely used. STA is, however, challenging due to its technical demands and the risk of injury to the sural nerve (SN). The purpose of this study was to identify the SN and its branches including their anatomical relationship to the STA as well as to describe an anatomical windows technique for STA including determination of the safe angle for screw insertion into the sustentaculum tali fragment. Methods: Thirty-two adult cadaveric legs were disarticulated at the knee and unpaired. STA was performed on each specimen. The anatomy and distribution of the sural nerve and its branches were identified in relation to the incision. Three surgical windows were identified and selected. Kirshner wires were inserted in pairs via each of the windows towards the center of the sustentaculum tali. The safe angle for wire insertion in relation to the SN or its branches was then measured as well as the appropriate intraoperative drilling angle. Results: The plantar branch presented in the distal window in none of the samples, while the dorsal branches presented in 37.5% and the main SN presented in only 6.25%. In the middle window, the dorsal branch presented most often (43.75%) followed by the plantar branch (25.00%) and the SN (21.88%). In the proximal window, the SN presented in 100% of the samples, while the dorsal branch presented in none and the plantar branch presented in about 15.63% of the specimens. All three windows had their own acceptable average angle for screw insertion towards the sustentaculum tali. Conclusions: The distal window is the safest for surgical approach and for calcaneal surgery screw fixation in terms of avoiding sural nerve injury. In addition, that window provides a wide working angle for screw fixation.